Jason Johnson - Academia.edu (original) (raw)
Papers by Jason Johnson
A therosclerosis and aneurysms are the leading causes of cardiovascular disease, the major source... more A therosclerosis and aneurysms are the leading causes of cardiovascular disease, the major source of mortality and morbidity worldwide. 1 Unstable atherosclerotic plaques are characterized by a relative preponderance of inflammatory cells and heightened proteolytic activity. 2,3 Clinically relevant abdominal aortic aneurysms (AAAs) are also associated with inflammation and matrix degradation. 4 Subsets of proinflam-matory macrophages are considered central to the pathogen-esis of the above inflammatory cardiovascular diseases, in part, through augmented release of matrix-degrading proteases and by decreased expression of their inhibitors. However, other macrophage subsets may play beneficial roles, for example, by facilitating smooth muscle cell recruitment, regulating neovascularization, and promoting extracellular matrix (ECM) formation/deposition. 5 Similarly, matrix metalloproteinases (MMPs), a group of proteases produced by macrophages and abundant in pathological cardiovascular tissues, 6 may also play a dual role. MMP knockout mice and other transgenic models show clear effects of individual MMPs on vascular repair and fibrous cap formation on the one hand or ECM destruction and hence destabilization of atherosclerotic lesions and aneu-rysm rupture on the other. These opposing effects of different MMPs probably underlie the disappointing results achieved Rationale: Atherosclerosis and aneurysms are leading causes of mortality worldwide. MicroRNAs (miRs) are key determinants of gene and protein expression, and atypical miR expression has been associated with many cardiovascular diseases; although their contributory role to atherosclerotic plaque and abdominal aortic aneurysm stability are poorly understood. Objective: To investigate whether miR-181b regulates tissue inhibitor of metalloproteinase-3 expression and affects atherosclerosis and aneurysms. Methods and Results: Here, we demonstrate that miR-181b was overexpressed in symptomatic human atherosclerotic plaques and abdominal aortic aneurysms and correlated with decreased expression of predicted miR-181b targets, tissue inhibitor of metalloproteinase-3, and elastin. Using the well-characterized mouse atherosclerosis models of Apoe −/− and Ldlr −/− , we observed that in vivo administration of locked nucleic acid anti-miR-181b retarded both the development and the progression of atherosclerotic plaques. Systemic delivery of anti-miR-181b in angiotensin II– infused Apoe −/− and Ldlr −/− mice attenuated aneurysm formation and progression within the ascending, thoracic, and abdominal aorta. Moreover, miR-181b inhibition greatly increased elastin and collagen expression, promoting a fibrotic response and subsequent stabilization of existing plaques and aneurysms. We determined that miR-181b negatively regulates macrophage tissue inhibitor of metalloproteinase-3 expression and vascular smooth muscle cell elastin production, both important factors in maintaining atherosclerotic plaque and aneurysm stability. Validation studies in Timp3 −/− mice confirmed that the beneficial effects afforded by miR-181b inhibition are largely tissue inhibitor of metalloproteinase-3 dependent, while also revealing an additional protective effect through elevating elastin synthesis. Conclusions: Our findings suggest that the management of miR-181b and its target genes provides therapeutic potential for limiting the progression of atherosclerosis and aneurysms and protecting them from rupture.
The international journal of biochemistry & cell biology, 2014
Atherosclerosis is an inflammatory disorder of the vasculature regulated by cytokines. Amongst th... more Atherosclerosis is an inflammatory disorder of the vasculature regulated by cytokines. Amongst the cytokines, IL-33 attenuates the development of atherosclerosis in mouse model systems via several mechanisms, including inhibition of macrophage foam cell formation and promotion of a Th1 to Th2 shift. Proteases produced by macrophages, such as matrix metalloproteinases and members of ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family, play potential roles in regulating atherosclerotic plaque stability. Despite such importance, the action of IL-33 on the expression of such proteases has not been analyzed. We have therefore investigated the effect of IL-33 on the expression of ADAMTS-1, -4 and -5 in human macrophages. Immunohistochemical analysis showed that these three proteases were expressed in human atherosclerotic lesions, particularly by macrophages and, to a lesser extent, by smooth muscle cells and endothelial cells. The expression of ADAMTS-1, -4 and...
Molecular Therapy — Methods & Clinical Development, 2014
Atherosclerotic plaque instability is precipitated by vascular smooth muscle cell apoptosis in th... more Atherosclerotic plaque instability is precipitated by vascular smooth muscle cell apoptosis in the fibrous cap, weakening it and leading to plaque rupture. We previously showed that reducing smooth muscle cell apoptosis with soluble N-cadherin (SNC) increased features of plaque stability. We have now identified the active site of SNC and examined whether a truncated form containing this site retains the antiapoptotic effect. SNC was mutated to prevent interaction with N-cadherin or fibroblast growth factor receptor (FGFR). Interaction with FGFR in the extracellular (EC) 4 domain of SNC was essential for the antiapoptotic effect. Therefore, we made a truncated form consisting of the EC4 domain. EC4 significantly reduced smooth muscle cell, macrophage, and endothelial cell apoptosis in vitro by ~70%, similar to SNC. Elevation of plasma levels of EC4 in male apolipoprotein E-deficient mice with existing atherosclerosis significantly reduced apoptosis in brachiocephalic artery plaques by ~50%. EC4 reduced plaque size and the incidence of buried fibrous layers and the macrophage:smooth muscle cell ratio (surrogate markers of plaque instability). Interaction of EC4 with FGFR induced potent antiapoptotic signaling in vitro and in vivo. EC4 modulates atherosclerosis in mice demonstrating its therapeutic potential for retarding plaque size and instability.
Cardiovascular research, 2006
Matrix metalloproteinases (MMPs) form a large family of enzymes that collectively can degrade all... more Matrix metalloproteinases (MMPs) form a large family of enzymes that collectively can degrade all components of the extracellular matrix, and there is widespread interest in developing MMP inhibitors for the prevention of atherosclerotic plaque rupture. We have therefore investigated the effects of a broad-spectrum MMP inhibitor, RS-130830, on plaque development and stability. This compound inhibits a wide range of MMPs at concentrations below 20 nmol/L. Apolipoprotein E knockout mice were fed a Western diet. Dietary administration of RS-130830 commenced at the same time as fat-feeding and continued for 8, 12, 26 or 36 weeks. To investigate the effect of RS-130830 on established plaques, mice were fed high-fat diet for 16 weeks before initiation of drug treatment and were terminated 20 weeks after this. Broad-spectrum MMP inhibition was associated with a significant increase in plaque area, but there was no change in the incidence of plaque rupture. There were unfavourable changes i...
Current opinion in lipidology, 2009
The varied behaviour of macrophages and foam cells during atherosclerosis and its clinical sequel... more The varied behaviour of macrophages and foam cells during atherosclerosis and its clinical sequelae prompt the question whether all these activities can be the property of a single cell population. Subsets of monocytes with distinct patterns of surface markers and behaviours during inflammation have recently been characterized and shown to have complementary roles during progression of atherosclerosis. A variety of macrophage phenotypes derived from these monocyte subsets in response to mediators of innate and acquired immunity have also been found in plaques. Based on functional properties and genomic signatures, they may have different impacts on facets of plaque development, including fibrous cap and lipid core formation. Monocyte and macrophage phenotypic diversity is important in atherogenesis. More work is needed to define consistent marker sets for the different foam cell phenotypes in experimental animals and humans. Cell tracking studies are needed to establish their relati...
Arteriosclerosis, thrombosis, and vascular biology, 2014
Apoptosis of vascular smooth muscle cells (VSMCs) contributes to thinning and rupture of the athe... more Apoptosis of vascular smooth muscle cells (VSMCs) contributes to thinning and rupture of the atherosclerotic plaque fibrous cap and is thereby associated with myocardial infarction. Wnt protein activation of β-catenin regulates numerous genes that are associated with cell survival. We therefore investigated Wnt/β-catenin survival signaling in VSMCs and assessed the presence of this pathway in human atherosclerotic plaques at various stages of the disease process. Wnt5a induced β-catenin/T-cell factor signaling and retarded oxidative stress (H₂O₂)-induced apoptosis in mouse aortic VSMCs. Quantification of mRNA levels revealed a >4-fold (P<0.05; n=9) increase in the expression of the Wnt/β-catenin responsive gene, Wnt1-inducible secreted protein-1 (WISP-1), which was dependent on cAMP response element-binding protein and sustained in the presence of H₂O₂. Exogenous WISP-1 significantly reduced H₂O₂-induced apoptosis by 43% (P<0.05; n=3) and was shown using silencing small int...
Mediators of inflammation, 2014
Matrix metalloproteinase-14 (MMP-14) promotes vulnerable plaque morphology in mice, whereas tissu... more Matrix metalloproteinase-14 (MMP-14) promotes vulnerable plaque morphology in mice, whereas tissue inhibitor of metalloproteinases-3 (TIMP-3) overexpression is protective. MMP-14(hi) TIMP-3(lo) rabbit foam cells are more invasive and more prone to apoptosis than MMP-14(lo) TIMP-3(hi) cells. We investigated the implications of these findings for human atherosclerosis. In vitro generated macrophages and foam-cell macrophages, together with atherosclerotic plaques characterised as unstable or stable, were examined for expression of MMP-14, TIMP-3, and inflammatory markers. Proinflammatory stimuli increased MMP-14 and decreased TIMP-3 mRNA and protein expression in human macrophages. However, conversion to foam-cells with oxidized LDL increased MMP-14 and decreased TIMP-3 protein, independently of inflammatory mediators and partly through posttranscriptional mechanisms. Within atherosclerotic plaques, MMP-14 was prominent in foam-cells with either pro- or anti-inflammatory macrophage ma...
Frontiers in immunology, 2014
Rupture of advanced atherosclerotic plaques accounts for most life-threatening myocardial infarct... more Rupture of advanced atherosclerotic plaques accounts for most life-threatening myocardial infarctions. Classical (M1) and alternative (M2) macrophage activation could promote atherosclerotic plaque progression and rupture by increasing production of proteases, including matrix metalloproteinases (MMPs). Lymphocyte-derived cytokines may be essential for generating M1 and M2 phenotypes in plaques, although this has not been rigorously tested until now. We validated the expression of M1 markers (iNOS and COX-2) and M2 markers (arginase-1, Ym-1, and CD206) and then measured MMP mRNA levels in mouse macrophages during classical and alternative activation in vitro. We then compared mRNA expression of these genes ex vivo in foam cells from subcutaneous granulomas in fat-fed immune-competent ApoE knockout (KO) and immune-compromised ApoE/Rag-1 double-KO mice, which lack all T and B cells. Furthermore, we performed immunohistochemistry in subcutaneous granulomas and in aortic root and brachi...
Journal of molecular and cellular cardiology, 2015
Elevation of intracellular cAMP concentration has numerous vascular protective effects that are i... more Elevation of intracellular cAMP concentration has numerous vascular protective effects that are in part mediated via actin cytoskeleton-remodelling and subsequent regulation of gene expression. However, the mechanisms are incompletely understood. Here we investigated whether cAMP-induced actin-cytoskeleton remodelling modulates VSMC behaviour by inhibiting expression of CCN1. In cultured rat VSMC, CCN1-silencing significantly inhibited BrdU incorporation and migration in a wound healing assay. Recombinant CCN1 enhanced chemotaxis in a Boyden chamber. Adding db-cAMP, or elevating cAMP using forskolin, significantly inhibited CCN1 mRNA and protein expression in vitro; transcriptional regulation was demonstrated by measuring pre-spliced CCN1 mRNA and CCN1-promoter activity. Forskolin also inhibited CCN1 expression in balloon injured rat carotid arteries in vivo. Inhibiting RhoA activity, which regulates actin-polymerisation, by cAMP-elevation or pharmacologically with C3-transferase, o...
The Journal of Thoracic and Cardiovascular Surgery, 2002
expression in cholesterol-fed pigs formation, cholesterol concentration, and vascular cell adhesi... more expression in cholesterol-fed pigs formation, cholesterol concentration, and vascular cell adhesion molecule 1
Circulation, 2005
Background-These studies examined the early time course of plaque development and destabilization... more Background-These studies examined the early time course of plaque development and destabilization in the brachiocephalic artery of the apolipoprotein E-knockout mouse, the effects of pravastatin thereon, and the effects of pravastatin on established unstable plaques. Methods and Results-Male apolipoprotein E-knockout mice were fed a high-fat, cholesterol-enriched diet from the age of 8 weeks. Animals were euthanized at 1-week intervals between 4 and 9 weeks of fat feeding. Acutely ruptured plaques were observed in the brachiocephalic arteries of 3% of animals up to and including 7 weeks of fat feeding but in 62% of animals after 8 weeks, which suggests that there is a sharp increase in the number of plaque ruptures at 8 weeks. These acute plaque ruptures then appear to heal and form buried fibrous caps; after 9 weeks of fat feeding, mice had 1.05Ϯ0.15 buried fibrous caps at a single site in the brachiocephalic artery. Pravastatin (40 mg/kg of body weight per day for 9 weeks; resultant plasma concentration 16Ϯ4 nmol/L) had no effect on plasma cholesterol concentration in fat-fed apolipoprotein E-knockout mice but reduced the number of buried fibrous caps by 43% (PϽ0.0001). In longer-term experiments, the delay of pravastatin treatment until unstable plaques had developed reduced the incidence of acute plaque rupture by 36% (PϽ0.0001). Conclusions-Plaque rupture occurs at high frequency in the brachiocephalic arteries of male apolipoprotein E-knockout mice after 8 weeks of fat feeding. Pravastatin treatment inhibits early plaque rupture and is also effective when begun after unstable plaques have developed. (Circulation. 2005;111:1422-1430.)
Atherosclerosis, 2010
While collagen, macrophage and T cell content of plaques of CCL3 KO chimeras were essentially sim... more While collagen, macrophage and T cell content of plaques of CCL3 KO chimeras were essentially similar to that of littermate controls, neutrophil adhesion to and presence in plaques was significantly attenuated (−60%, P = 0.001). Under non inflammatory conditions circulating neutrophil numbers did not differ between WT and CCL3 KO mice, whereas they were markedly decreased in CCL3 KO mice upon LPS treatment. Kinetic analysis of neutrophils after cyclosphosphamide treatment showed accelerated depletion in CCL3 KO mice pointing to a reduced neutrophil half life. CCL3 KO neutrophils were less responsive towards the neutrophil chemo-attractant KC. Taken together our data indicate that under conditions of acute inflammation leukocyte derived CCL3 can induce neutrophil chemotaxis towards the atherosclerotic plaque, thereby accelerating lesion formation.
A therosclerosis and aneurysms are the leading causes of cardiovascular disease, the major source... more A therosclerosis and aneurysms are the leading causes of cardiovascular disease, the major source of mortality and morbidity worldwide. 1 Unstable atherosclerotic plaques are characterized by a relative preponderance of inflammatory cells and heightened proteolytic activity. 2,3 Clinically relevant abdominal aortic aneurysms (AAAs) are also associated with inflammation and matrix degradation. 4 Subsets of proinflam-matory macrophages are considered central to the pathogen-esis of the above inflammatory cardiovascular diseases, in part, through augmented release of matrix-degrading proteases and by decreased expression of their inhibitors. However, other macrophage subsets may play beneficial roles, for example, by facilitating smooth muscle cell recruitment, regulating neovascularization, and promoting extracellular matrix (ECM) formation/deposition. 5 Similarly, matrix metalloproteinases (MMPs), a group of proteases produced by macrophages and abundant in pathological cardiovascular tissues, 6 may also play a dual role. MMP knockout mice and other transgenic models show clear effects of individual MMPs on vascular repair and fibrous cap formation on the one hand or ECM destruction and hence destabilization of atherosclerotic lesions and aneu-rysm rupture on the other. These opposing effects of different MMPs probably underlie the disappointing results achieved Rationale: Atherosclerosis and aneurysms are leading causes of mortality worldwide. MicroRNAs (miRs) are key determinants of gene and protein expression, and atypical miR expression has been associated with many cardiovascular diseases; although their contributory role to atherosclerotic plaque and abdominal aortic aneurysm stability are poorly understood. Objective: To investigate whether miR-181b regulates tissue inhibitor of metalloproteinase-3 expression and affects atherosclerosis and aneurysms. Methods and Results: Here, we demonstrate that miR-181b was overexpressed in symptomatic human atherosclerotic plaques and abdominal aortic aneurysms and correlated with decreased expression of predicted miR-181b targets, tissue inhibitor of metalloproteinase-3, and elastin. Using the well-characterized mouse atherosclerosis models of Apoe −/− and Ldlr −/− , we observed that in vivo administration of locked nucleic acid anti-miR-181b retarded both the development and the progression of atherosclerotic plaques. Systemic delivery of anti-miR-181b in angiotensin II– infused Apoe −/− and Ldlr −/− mice attenuated aneurysm formation and progression within the ascending, thoracic, and abdominal aorta. Moreover, miR-181b inhibition greatly increased elastin and collagen expression, promoting a fibrotic response and subsequent stabilization of existing plaques and aneurysms. We determined that miR-181b negatively regulates macrophage tissue inhibitor of metalloproteinase-3 expression and vascular smooth muscle cell elastin production, both important factors in maintaining atherosclerotic plaque and aneurysm stability. Validation studies in Timp3 −/− mice confirmed that the beneficial effects afforded by miR-181b inhibition are largely tissue inhibitor of metalloproteinase-3 dependent, while also revealing an additional protective effect through elevating elastin synthesis. Conclusions: Our findings suggest that the management of miR-181b and its target genes provides therapeutic potential for limiting the progression of atherosclerosis and aneurysms and protecting them from rupture.
The international journal of biochemistry & cell biology, 2014
Atherosclerosis is an inflammatory disorder of the vasculature regulated by cytokines. Amongst th... more Atherosclerosis is an inflammatory disorder of the vasculature regulated by cytokines. Amongst the cytokines, IL-33 attenuates the development of atherosclerosis in mouse model systems via several mechanisms, including inhibition of macrophage foam cell formation and promotion of a Th1 to Th2 shift. Proteases produced by macrophages, such as matrix metalloproteinases and members of ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family, play potential roles in regulating atherosclerotic plaque stability. Despite such importance, the action of IL-33 on the expression of such proteases has not been analyzed. We have therefore investigated the effect of IL-33 on the expression of ADAMTS-1, -4 and -5 in human macrophages. Immunohistochemical analysis showed that these three proteases were expressed in human atherosclerotic lesions, particularly by macrophages and, to a lesser extent, by smooth muscle cells and endothelial cells. The expression of ADAMTS-1, -4 and...
Molecular Therapy — Methods & Clinical Development, 2014
Atherosclerotic plaque instability is precipitated by vascular smooth muscle cell apoptosis in th... more Atherosclerotic plaque instability is precipitated by vascular smooth muscle cell apoptosis in the fibrous cap, weakening it and leading to plaque rupture. We previously showed that reducing smooth muscle cell apoptosis with soluble N-cadherin (SNC) increased features of plaque stability. We have now identified the active site of SNC and examined whether a truncated form containing this site retains the antiapoptotic effect. SNC was mutated to prevent interaction with N-cadherin or fibroblast growth factor receptor (FGFR). Interaction with FGFR in the extracellular (EC) 4 domain of SNC was essential for the antiapoptotic effect. Therefore, we made a truncated form consisting of the EC4 domain. EC4 significantly reduced smooth muscle cell, macrophage, and endothelial cell apoptosis in vitro by ~70%, similar to SNC. Elevation of plasma levels of EC4 in male apolipoprotein E-deficient mice with existing atherosclerosis significantly reduced apoptosis in brachiocephalic artery plaques by ~50%. EC4 reduced plaque size and the incidence of buried fibrous layers and the macrophage:smooth muscle cell ratio (surrogate markers of plaque instability). Interaction of EC4 with FGFR induced potent antiapoptotic signaling in vitro and in vivo. EC4 modulates atherosclerosis in mice demonstrating its therapeutic potential for retarding plaque size and instability.
Cardiovascular research, 2006
Matrix metalloproteinases (MMPs) form a large family of enzymes that collectively can degrade all... more Matrix metalloproteinases (MMPs) form a large family of enzymes that collectively can degrade all components of the extracellular matrix, and there is widespread interest in developing MMP inhibitors for the prevention of atherosclerotic plaque rupture. We have therefore investigated the effects of a broad-spectrum MMP inhibitor, RS-130830, on plaque development and stability. This compound inhibits a wide range of MMPs at concentrations below 20 nmol/L. Apolipoprotein E knockout mice were fed a Western diet. Dietary administration of RS-130830 commenced at the same time as fat-feeding and continued for 8, 12, 26 or 36 weeks. To investigate the effect of RS-130830 on established plaques, mice were fed high-fat diet for 16 weeks before initiation of drug treatment and were terminated 20 weeks after this. Broad-spectrum MMP inhibition was associated with a significant increase in plaque area, but there was no change in the incidence of plaque rupture. There were unfavourable changes i...
Current opinion in lipidology, 2009
The varied behaviour of macrophages and foam cells during atherosclerosis and its clinical sequel... more The varied behaviour of macrophages and foam cells during atherosclerosis and its clinical sequelae prompt the question whether all these activities can be the property of a single cell population. Subsets of monocytes with distinct patterns of surface markers and behaviours during inflammation have recently been characterized and shown to have complementary roles during progression of atherosclerosis. A variety of macrophage phenotypes derived from these monocyte subsets in response to mediators of innate and acquired immunity have also been found in plaques. Based on functional properties and genomic signatures, they may have different impacts on facets of plaque development, including fibrous cap and lipid core formation. Monocyte and macrophage phenotypic diversity is important in atherogenesis. More work is needed to define consistent marker sets for the different foam cell phenotypes in experimental animals and humans. Cell tracking studies are needed to establish their relati...
Arteriosclerosis, thrombosis, and vascular biology, 2014
Apoptosis of vascular smooth muscle cells (VSMCs) contributes to thinning and rupture of the athe... more Apoptosis of vascular smooth muscle cells (VSMCs) contributes to thinning and rupture of the atherosclerotic plaque fibrous cap and is thereby associated with myocardial infarction. Wnt protein activation of β-catenin regulates numerous genes that are associated with cell survival. We therefore investigated Wnt/β-catenin survival signaling in VSMCs and assessed the presence of this pathway in human atherosclerotic plaques at various stages of the disease process. Wnt5a induced β-catenin/T-cell factor signaling and retarded oxidative stress (H₂O₂)-induced apoptosis in mouse aortic VSMCs. Quantification of mRNA levels revealed a >4-fold (P<0.05; n=9) increase in the expression of the Wnt/β-catenin responsive gene, Wnt1-inducible secreted protein-1 (WISP-1), which was dependent on cAMP response element-binding protein and sustained in the presence of H₂O₂. Exogenous WISP-1 significantly reduced H₂O₂-induced apoptosis by 43% (P<0.05; n=3) and was shown using silencing small int...
Mediators of inflammation, 2014
Matrix metalloproteinase-14 (MMP-14) promotes vulnerable plaque morphology in mice, whereas tissu... more Matrix metalloproteinase-14 (MMP-14) promotes vulnerable plaque morphology in mice, whereas tissue inhibitor of metalloproteinases-3 (TIMP-3) overexpression is protective. MMP-14(hi) TIMP-3(lo) rabbit foam cells are more invasive and more prone to apoptosis than MMP-14(lo) TIMP-3(hi) cells. We investigated the implications of these findings for human atherosclerosis. In vitro generated macrophages and foam-cell macrophages, together with atherosclerotic plaques characterised as unstable or stable, were examined for expression of MMP-14, TIMP-3, and inflammatory markers. Proinflammatory stimuli increased MMP-14 and decreased TIMP-3 mRNA and protein expression in human macrophages. However, conversion to foam-cells with oxidized LDL increased MMP-14 and decreased TIMP-3 protein, independently of inflammatory mediators and partly through posttranscriptional mechanisms. Within atherosclerotic plaques, MMP-14 was prominent in foam-cells with either pro- or anti-inflammatory macrophage ma...
Frontiers in immunology, 2014
Rupture of advanced atherosclerotic plaques accounts for most life-threatening myocardial infarct... more Rupture of advanced atherosclerotic plaques accounts for most life-threatening myocardial infarctions. Classical (M1) and alternative (M2) macrophage activation could promote atherosclerotic plaque progression and rupture by increasing production of proteases, including matrix metalloproteinases (MMPs). Lymphocyte-derived cytokines may be essential for generating M1 and M2 phenotypes in plaques, although this has not been rigorously tested until now. We validated the expression of M1 markers (iNOS and COX-2) and M2 markers (arginase-1, Ym-1, and CD206) and then measured MMP mRNA levels in mouse macrophages during classical and alternative activation in vitro. We then compared mRNA expression of these genes ex vivo in foam cells from subcutaneous granulomas in fat-fed immune-competent ApoE knockout (KO) and immune-compromised ApoE/Rag-1 double-KO mice, which lack all T and B cells. Furthermore, we performed immunohistochemistry in subcutaneous granulomas and in aortic root and brachi...
Journal of molecular and cellular cardiology, 2015
Elevation of intracellular cAMP concentration has numerous vascular protective effects that are i... more Elevation of intracellular cAMP concentration has numerous vascular protective effects that are in part mediated via actin cytoskeleton-remodelling and subsequent regulation of gene expression. However, the mechanisms are incompletely understood. Here we investigated whether cAMP-induced actin-cytoskeleton remodelling modulates VSMC behaviour by inhibiting expression of CCN1. In cultured rat VSMC, CCN1-silencing significantly inhibited BrdU incorporation and migration in a wound healing assay. Recombinant CCN1 enhanced chemotaxis in a Boyden chamber. Adding db-cAMP, or elevating cAMP using forskolin, significantly inhibited CCN1 mRNA and protein expression in vitro; transcriptional regulation was demonstrated by measuring pre-spliced CCN1 mRNA and CCN1-promoter activity. Forskolin also inhibited CCN1 expression in balloon injured rat carotid arteries in vivo. Inhibiting RhoA activity, which regulates actin-polymerisation, by cAMP-elevation or pharmacologically with C3-transferase, o...
The Journal of Thoracic and Cardiovascular Surgery, 2002
expression in cholesterol-fed pigs formation, cholesterol concentration, and vascular cell adhesi... more expression in cholesterol-fed pigs formation, cholesterol concentration, and vascular cell adhesion molecule 1
Circulation, 2005
Background-These studies examined the early time course of plaque development and destabilization... more Background-These studies examined the early time course of plaque development and destabilization in the brachiocephalic artery of the apolipoprotein E-knockout mouse, the effects of pravastatin thereon, and the effects of pravastatin on established unstable plaques. Methods and Results-Male apolipoprotein E-knockout mice were fed a high-fat, cholesterol-enriched diet from the age of 8 weeks. Animals were euthanized at 1-week intervals between 4 and 9 weeks of fat feeding. Acutely ruptured plaques were observed in the brachiocephalic arteries of 3% of animals up to and including 7 weeks of fat feeding but in 62% of animals after 8 weeks, which suggests that there is a sharp increase in the number of plaque ruptures at 8 weeks. These acute plaque ruptures then appear to heal and form buried fibrous caps; after 9 weeks of fat feeding, mice had 1.05Ϯ0.15 buried fibrous caps at a single site in the brachiocephalic artery. Pravastatin (40 mg/kg of body weight per day for 9 weeks; resultant plasma concentration 16Ϯ4 nmol/L) had no effect on plasma cholesterol concentration in fat-fed apolipoprotein E-knockout mice but reduced the number of buried fibrous caps by 43% (PϽ0.0001). In longer-term experiments, the delay of pravastatin treatment until unstable plaques had developed reduced the incidence of acute plaque rupture by 36% (PϽ0.0001). Conclusions-Plaque rupture occurs at high frequency in the brachiocephalic arteries of male apolipoprotein E-knockout mice after 8 weeks of fat feeding. Pravastatin treatment inhibits early plaque rupture and is also effective when begun after unstable plaques have developed. (Circulation. 2005;111:1422-1430.)
Atherosclerosis, 2010
While collagen, macrophage and T cell content of plaques of CCL3 KO chimeras were essentially sim... more While collagen, macrophage and T cell content of plaques of CCL3 KO chimeras were essentially similar to that of littermate controls, neutrophil adhesion to and presence in plaques was significantly attenuated (−60%, P = 0.001). Under non inflammatory conditions circulating neutrophil numbers did not differ between WT and CCL3 KO mice, whereas they were markedly decreased in CCL3 KO mice upon LPS treatment. Kinetic analysis of neutrophils after cyclosphosphamide treatment showed accelerated depletion in CCL3 KO mice pointing to a reduced neutrophil half life. CCL3 KO neutrophils were less responsive towards the neutrophil chemo-attractant KC. Taken together our data indicate that under conditions of acute inflammation leukocyte derived CCL3 can induce neutrophil chemotaxis towards the atherosclerotic plaque, thereby accelerating lesion formation.